Double-storey extensions · Seaham

Double-storey extensions in Seaham

Our double-storey extensions service covers Seaham and the rest of County Durham. You get a fixed price in writing for the agreed specification, and one person co-ordinating the trades.

Covering Seaham

Our coverage around Seaham (SR7) also includes Houghton-le-Spring (5 miles to the west) and Sunderland.

Homes in the North East

In the North East, terraces, semis and bungalows all offer room to extend, with stone-built villages and conservation areas in parts of County Durham and Northumberland.

What does a double-storey extension involve?

A double-storey extension adds new rooms on both the ground and first floor in one build, typically a larger kitchen or living space downstairs and an extra bedroom or bathroom above. Because the roof and foundations are shared, the cost per square metre is usually lower than a single-storey extension.

  • Measured survey, design and planning drawings
  • Householder planning application
  • Windows, insulation, plastering, electrics and plumbing

How much should I budget for a double-storey extension?

What double-storey extensions typically cost. These are guide ranges; the written quote for your house replaces them.

Double-storey extensionsGuide price incl. VAT
Standard specification£2,400 to £2,900 per m²
Good specification£2,900 to £3,400 per m²
High specification£3,400 to £3,850 per m²

What approvals does a double-storey extension need in England?

In England we deal with the council’s planning team for permission or a lawful development certificate, with building control (the council or a registered building control approver) for inspections, and with neighbours under the Party Wall etc. Act 1996 where it applies.

Two-storey rear extensions can sometimes be permitted development in England (no more than 3 m deep, at least 7 m from the rear boundary, roof pitch to match), but most two-storey and all two-storey side extensions need householder planning permission.

What should Seaham homeowners check first?

  • Neighbours’ light is assessed using the 45-degree guide many councils use.
  • The first-floor link can mean moving a bathroom or reshaping the landing.

What are the steps?

  1. Send us the details. Give us a postcode, a rough idea of size and some photos, by phone, form or the guide price tool.
  2. We visit and measure. A surveyor checks the house, the boundaries and the ground, and discusses what is realistic.
  3. Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
  4. Construction and completion. One site lead co-ordinates every trade through to the building control certificate.

What people ask before starting

How much does a two-storey extension cost?

Typically about £2,400 to £3,850 per square metre of new floor area including VAT. A 40 m² extension across two floors is often around £100,000 to £150,000 depending on specification.

Does a two-storey extension need planning permission?

Usually yes. In England some two-storey rear extensions are permitted development, but side extensions over one storey always need planning permission.

Can you visit a house in Seaham to quote?

Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.

Double-storey extensions near Seaham

Learn more about double-storey extensions, or see every project we cover in Seaham.

Planning an extension, loft or new home?

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